1. Field of the Invention
The present invention relates to a fuel tank device for storing liquid fuel.
2. Description of the Related Art
Conventionally, a fuel tank device having a float valve to close a breather pipe when a liquid level of liquid fuel having been supplied thereinto is raised to a certain level has been proposed (See JP2004-189074A).
The inside of the fuel tank device is filled with liquid fuel and fuel evaporative emissions generated by evaporation of the liquid fuel into air in the fuel tank device. Accordingly, when a volume of the liquid fuel inside the fuel tank device is increased by feeding the liquid fuel, the fuel evaporative emissions are discharged from the inside of the fuel tank device through the breather pipe. In a fuel tank device provided in a vehicle, the discharged fuel evaporative emissions are charged in a canister until the float valve is closed due to a fill-up when feeding the liquid fuel. The fuel evaporative emissions charged in the canister are purged and sucked from an engine intake system into an engine to be combusted after the engine starts.
The fuel tank device is often arranged under a seat or seats where it is relatively easy to secure a capacity, in the vehicle. In order to increase the capacity with the fuel tank device being arranged under the seat or the seats without interfering with the latter, a ground clearance is rendered as small as possible.
There are vehicles such as a front engine rear-wheel drive vehicle (an FR vehicle) where power of an engine placed in the front is transferred to a rear wheel via a propeller shaft. In such vehicles, too, the fuel tank device is arranged under a seat above a propeller shaft extending along the center of the vehicle not to interfere with the propeller shaft. In order that the fuel tank device does not interfere with the propeller shaft while the ground clearance of the fuel tank device is maintained as small as possible, a part of the bottom of the fuel tank device is raised. The propeller shaft is designed to be passed under the raised bottom. The fuel tank device is shaped into a so called saddle.
By being rendered a saddle, it is considered that the fuel tank device has a first fuel chamber located on one end thereof, a second fuel chamber located on the other end thereof and a raised bottom communication chamber communicating with the first fuel chamber through the second fuel chamber.
The fuel evaporative emissions need to be discharged from the fuel tank device while the liquid fuel is supplied. Therefore, the communication chamber is provided with the float valve to which the breather pipe is connected. The fuel evaporative emissions are discharged from the breather pipe. Even if a work floor in a filling station such as a gas station, etc., is slightly sloped so that a vehicle is slightly inclined, an appropriate filling amount can be secured by providing the float valve in the communication chamber. If the float valve is arranged in the first fuel chamber or the second fuel chamber, a filling amount varies in accordance with the inclination of the vehicle.
When filled, the liquid fuel is fed to the first fuel chamber via a filler pipe. From the first fuel chamber, the liquid fuel is fed to the second fuel chamber via the communication chamber. Since the communication chamber has a raised bottom, the height from the bottom to the float valve is forced to be low. Consequently, the liquid fuel flown from the first fuel chamber into the second fuel chamber can make contact with the float valve. As a result, the float valve is closed and the fuel evaporative emissions are not discharged so that an inner pressure is increased. The liquid level of the liquid fuel rises in the filler pipe. When the liquid level of the liquid fuel reaches the tip of a fuel nozzle, the fuel nozzle detects the liquid level and stops supplying the fuel. At this time, at least, the liquid fuel in the second fuel chamber does not reach a filled-up level. Therefore, an untimely automatic stop is made to occur. It is preferable to eliminate an occurrence of such an untimely automatic stop as much as possible in order to carry out a smooth filling operation.